Helium Ion Modified Luminescence and Robust Valley Polarization of Atomically Thin MoS2

We show a systematic study of the impact of focused helium ions on the optical, vibrational, and valleytronic properties of atomically thin MoS2. The shifting of the first-order Raman modes are explained by a phonon confinement model introducing an effective interdefect distance. We perform ab-initio density functional theory calculations on a variety of defect related morphologies to explain an additional luminescence peak by O2 molecules chemisorbed at monosulphur vacancies. We further observe that an interdefect distance of the size of the free exciton Bohr radius results in a significant reduction of valley polarization, most likely caused by strong intervalley scattering.     «

We show a systematic study of the impact of focused helium ions on the optical, vibrational, and valleytronic properties of atomically thin MoS2. The shifting of the first-order Raman modes are explained by a phonon confinement model introducing an effective interdefect distance. We perform ab-initio density functional theory calculations on a variety of defect related morphologies to explain an additional luminescence peak by O2 molecules chemisorbed at monosulphur vacancies. We further obser...     »